Hydraulic pump or motor



y 1939- E; K. BENEDEK 1 2,165,126 I HYDRAULIC PUMP OR MOTOR Filed Oct. 21, 1935 3 Sheets-Sheet 1 INVENTO 1 151. ILEKKEJ ENEDEK;

QATI'ORNEY.

' J ly 1939- E. K. BENEDE'K HYDRAULIC PUMP 0R MOTOR Filed Oct. 21, 1935 3 Sheets-Sheet 2 a l1 a M s m 4 I? 4/ IIHI m w m 4 1/ III ' ELEKKDENEDEK- "44"ATTORNEY 47R moron a Sheets-Sheet} QATTORNEY.

July 4, 1939. s. K. BENEDEK HYDRAULIC PUMP Filed Oct. 21, 19:55

I t5 portion lc of the housing,

Patented July 4, 1939 UNITED. STATES PATENT orncr.

on moron. I

Elek x. Benedek. Biron-us, Ohio Application mm: :1. ms, Serial No. 45,908 I 12 Claims- (cl. 103-16l) This invention relates to rotary radial piston hydraulic pump and motors, the principal object being to provide a highly eflicient and compact pump or motor of thischaracter, comprised of simple and rugged parts which may be manuiactured economically from readily available materials.

Another object to provide a; pump or motor employing a minimum of parts, and of which the parts may be assembled and disassembled more easily and manufactured by quantity methods with accuracy assuring fitting into proper operating relations.

Another object is to provide an improved bar- ,rel mounting, a simplified and rugged reactance means tor cooperation therewith, and'a simplifle positive coupling therebetween.

Still another object is to guide the piston heads efliciently and to effect load transmission between the barrel and rotary reactance by rolling friction instead of sliding friction.

Other objects and advantages will become apparent from the specification wherein reference is made to the drawings, in which:

Fig. 1 is a horizontal longitudinal sectional view of a pump or motor embodying the prlncipleso! the present invention; I

Fig. 2 is a vertical, cross sectional view and is taken on a plane indicated by the line 22 in Fig. 1, the barrel thereof being shown in a slight- 1y different rotated position than in Fig. 1;

Fig. 3 is a longitudinal sectional-view of the reactance means illustrated in Fig. 1;

Fig. 4 is a sectional view taken on a plane indicated by the line ll in Fig. 3; and] Fig. 5 is a fragmentary plan view of the'barrel and flange, viewed from the line 5-5 in Fig. 2.

For the purposes of illustration the present structure will be described as a pump, its opera-,

. tion as a motor being'readily apparent therefrom.

Referring to thedrawings, the pump structure is enclosed in a rigid weight supporting housing I, having an annular wall portion In. terminating at one end in a radial flange wall lb, the flange wall, in turn, terminating inwardly in'a rigidhub portion la, in which the main fluid circuit ports for connecting the pump to an'external fluid circut are provided, as will'later be described. The opposite end of the housing I is closed by a rigid cover 2 which may be secured to the end wall of the portion'Ja by suitable bolts, or other means, not shown.

A rigid valve pintle 3, having an enlarged shank portion 3a, is mounted at its shank inthe hub the shank being fixedly in the shank portion 3a with the other reversible race portion 317 and taper of the pintle,

. spectively,

secured in a suitable axial bore formed in. the hub lc. The pintle extends from the shank portion Ia into and coaxial with the housing portion In and has a portion adjacent the shank providing a large diameter bearing race 3b. On the op-' .5 posite or free end of the pintle l is a bearing race 3c; Between the race portions of the pintle is a valve portion 841 which is tapered toward the tree end of the pintle. In the pintle valve portion 3d 4 are reversible valve ports 4 and '5 which are sep- 10 arated from each other by suitable valve or timing bridges, as better illustrated in 2. I The valve port 4 is in communication with iongitudinally extending ducts 6 which are formed" in the pintle and communicate, tion la. thereof, with one. reversible main fluid port of the pump. The other valve port! is in communication with longitudinal ducts I which also are formed in the p tie and communicate main fluidport of the pump. Thus the ducts 6 and 'l, with the valve ports 4 and 5, and the main ports, not shown, in the shank portion Ia of. the pintle, form the internal fluid circuit in the usual manner. to the large shank'portion 3a and the ducts 6 and I can be drilled in converging direction so that the pintle provides a substantially constant strength beam. 1 p I Mounted within the ho hi: I in coaxial relation with respect to the pintle'3 is a cylinder bar, rel or rotor l0 having a tapered axial bore the wall of which is complementary to. and hydraulically fits the valve portion 3d of the pintle, the end of the bore adjacent the free end of the pintle being sealed for retaining fluid for hydrostatic balance of the pintle, as will later be described.

The barrel ID has a radial flange ll, preferably forged integral therewith, the flange having a plurality of circumferentially spaced radial guideways I la. In the barrel, in the zone of the flange and aligned one witheach guideway, are radial cylinders l2, each of which has a cylinder port II for cooperation successively with the ports 4 and 5 of the pintle subsequent upon rotation of the barrel. a g

For the purpose of constraining the barrel and pintle to positive coaxial relation with-positive, accurate radial capillary clearance between the valve portion 3a. of the pintle and bore wall of the barrel, the barrel is provided with, internal bearing race surfaces lllb and I0, these races being aligned radially with the races 8b and 30 reof the pintle. Sets of capillary cageand I6 respectively are inless needle rollers in the shank porf terp osed between the radially aligned races of the pintle and barrel.. The races 31) and 3c are preferably in the form of annular troughs formed on the pintle, the end walls of the troughs constraining the respective sets of needle rollers in proper position longitudinally of the pintle. By constraining the barrel and pintle to fixed coaxial relation withpositive radial clearance space hetween the pintle valve portion and barrel, bore circuit, and

wall by the capillary rollers, any inaccuraciesin manufacture which would otherwise cause misalignment of the pintle and barrel: are prevented;

In order to maintain the pintle in hydrostatic balance, the pintle is provided with a central duct II which is in communication with the instantaneous'pressureducts of the internal fluid the pintle into the dead end of the ,barrel bore, as more fully described in my co-pending application, Ser. No. 754,753, filed-November 26, 1934.

Thus the operating pressure fluid is continuously fed-into the .dead end. bore of the barrel l0 and flows into the capillary clearance space between the pintle valve portion and barrel bore wall and maintains fluid at line pressure therebetween.

By maintaining hydrostatic balance in this manner, a heavy hydraulic pressure thrust iscreated against the dead end of the barrel bore and urges the barrel to the right in Fig. 1.

For withstanding this thrustand providing for accurate adjustment of the barrel longitudinally of the pintle so as 'to maintain the proper clearance space between the valve portion 3d and barrel bore wall, the barrel is rotatably mounted .in the housing on sets of Tyso I less rollers I8 and I9 respectively. For effecting the proper-mounting of the barrel in the rollers l8 and IS, the end portion of the barrel is in radial alignment with the race I 0b to form a suitable annular shoulder 20 and radial shoulder due to their tapered form and angular disposition, are operable to resist radial load and axial 1 thrust of the barrel toward the shank 30. At the opposite end of the barrel is acorresponding 'a'nnular shoulder'26 and radial shoulder 21 accommodating the inner face 28 of, the set/ of rollers IS. The end cover 2 is provided with an internal annular shoulder 29 and radial shoulder .30 which accommodate the outer race 3| of the set of rollers -19. The set of rollers I 9 is disposed so as to resist'ifadial load and thrusts of the barrel in the direction opposite'to the set of bearings l8, especially that caused by the pressure fluid in the barrel bore.-

' Near its outer margin the cover 2 is provided with. an annular shoulder 32 coaxial with the shoulder 29. The portion (A correspondingly provided with an accurately positioned shoulder '33coope'rable with the' shoul-' der 32 for locating the end cover 2 in proper I position on the housing.

,By the introductionof proper shims between the end of the housing portion la and marginal-face ofthe cover 2 the barrel in may be adjusted axially for providing the proper tightness of the bearings l8 and I9. By eliminating undue radial slackness in the bearings 18- and discharges through the free end of 'Correspondingly,

. the tapered valve formed at the one setting so that all parts theretapered cageried in the cylinders rotatably mounted inthebore of la of the housing is.

I 9, the barrel is supported position in the casing and movement of the barrel axially in the direction to tighten the bearings l8 and I9 reduces the radial clearance between'the tapered pintle and the tapered valve bore wall and also centers the barrel more accurately with respect to the pintle so that the radial clearance ismore uniform. The bearings l5 and IS, in turn, do not resist axial movement of the barrel but constrain the pintle and barrel to coaxial relation in all adjusted positions and under hydrostatic deflecting forces so that, whatever total. radial clearance is provided, it will be uniformly distributed circumferentially of the valve pintle. The bearings l5 and I6 also draw the pintle to proper coaxial relation in the barrel so as to overcome manufacturing inaccuracies. Thus there is maintained proper radial clearance between the valve portion 3b and barrel bore wall so that wear may be compensated.

Certain advantages of the specific structure illustrated should be noted.

First, by .settingthe housing I in a suitable rotary carrier, the bore for the pintle shank-3a may be drilled in the hub lo and the shoulders 23 and 33 may be formed at the same setting so that all circular fitting parts are absolutely concentric or coaxial w'th respect to each other. the barrel may be mounted in by-its impeller shaft and the 26, the races lb and 100, and portion of the barrel bore a suitable carrier shoulders 20 and of are in coaxial relation. Next, theend cover 2 is turned at a single setting with the shoulder 32 and shoulder 29 in absolute coaxial relation.

Thus, when the parts are assembled, all are necessarily in coaxial relation with respect to each other and accuracy in manufacture and assembly is assured.

Referring next to the pistons and reactance means of the pump, radial pistons 40 are carfespectively. Each of the pistons 40 has a crosshead 4| with cylindrical end walls, axes of the end walls being parallel to the axis of the associated piston and having flat lateral faces. The radial guideways Ila have cylindrical guide walls, as better illustratedin Fig. 5, ior'engaging the cylindrical end walls of the heads 4| and accommodate the piston heads for reciprocation radially of the barrel while relieving the pistons 40 from torque transmis-: sion and preventing lateral vibration and 'misalignment ofthe heads. Each piston crosshead 4| has a transverse bore in which'is accommodated an operating cross pin 42. The pin 42 is the associated crosshead on capillary cageless needle rollers 43 which are retained in the crosshead bore by suitable retaining washers, not shown. Each crosspin 42, in turn, has a large diameter central portion substantially coextensive with the cross head and reduced diameter end portions 42a coaxial with the larger central portion so as to present radial guide shoulders 42b, at the juncture of the centraland reduced end portions, the shoulders merging with the reduced end portions 42a with a very slight fillet.

For cooperation with the pins 42, there is provided an adjustablerotary reactance means thereby. Accuratecomprising apair of mated, oppositely positioned, symmetrical one-piece reactance rings 45; each 7 of which has an annular'reactance groove 46 open toward the piston heads for receiving the 7s spect. to each other.

- the grooves ends 420 of the cross pins and forming a reactance track therefor. The adjacent faces 45:: of the rings 45 extend radially and lie snugly'alongside the flange H and lateral flat faces of the crossheads 4|. The radius of curvature between the radially inward trackwalls of the grooves 48 and radial face 450. of the ring 45 are slightly greater than the radius of the fillets between the shoulders 42b and end portions 42a of the crosspins for effecting proper guiding relation with the crosspins to prevent skewing of the pins in .the grooves.

The rotary reactance rings 45 are mounted on heavy duty bearings, such as ball bearings 41, within a pair of stator rings 48, the ball bearings operating in suitable grooves in the rings 45 and 48. The ball grooves are of slightly greater radius than the balls so that slight axial selfadjustment of therings 45 is provided. Each reactance ring 45 and its cooperating stator ring 48 is a separate and complete self-contained ball bearing assembly, the ring 48 being the outer race and the ring 45 being the inner race. The races 45 andi48 are formed with hearing grooves for receiving the-balls 41 so that the sides of the groove cooperate with the associated balls for constraining the inner and outer races of each assembly from relative axial separation. Thus a pair of axially separable reactance sub-units are provided which together form the reactance means of the pump.

The rings 48 are provided at their adjacent faces with accurately formed and machined surfaces, as indicated at 48, so that theymay be positioned readily in coaxial relation with re-" They are likewise provided with sets of aligned longitudinal bores accommodating suitable bolts 50 for securing drawing and clamping the rings 48 together to form a unitary structure, lock washers 5| being inter posed'between the heads of the bolts andcorresponding ring 48 to maintain the rings rigidly fixed in position with respect to each other. Each of the rings 48 is provided on its outer surface withv parallel tangential slide bearing surfaces 48a at diametrically opposite positions for cooperation with corresponding slide bearing surfaces within the annular wall portion la of the housing, as better illustrated in Fig. 2 for mounting the reactance stator rings 48 so that they may be shifted'as a unit to diiferen't positions of eccentricity with respect to the pintle axis while constrained to' positions in which their axis is parallel to the pintle axis and in a plane through the pintle axis and dead center line of the pintle bridges. Suitable control rods 52 are secured to the rings 48 and extend through suitable bores in the housing portion Ia so that the stroke of the pump may. be adjusted-from the outside.

In some instances it is desirable, especially upon starting and stopping, that a positive driving connection be provided between the barrel and reactance-rings 45. For this purpose holes 55 are provided in the-flange H, the holes being evenly distributedmidway between adjacent pistons and being positioned radially in the zone of 45 The rings 45 are provided with dead end pin receiving bores 56 which open through the end walls of the grooves 45, the 9 bores 55 of the two rings being arranged in pairs and the bores of each pair being aligned axially of the rings with respect to each other. Cylindrical dowel pins 51 are disposed within the pairs of aligned bores 56 respectively, and extend amuse parts.

through the openings 55, and are held in position consequent upon securing therings '48 in fixed axial position with respect to each other. The dowel pins 51 fit into the associated bores 58 with slight clearance -radiailyof the pins so as to permit very slight and limited relative rotation of the rings 45 with respect to each other but this relative rotation is not suflicient to be noticeable and appreciably affect the central porition of the dowel pins where they engage the barrel flange. This clearance is only sumcient to permit light capillary oil films to form around the ends of the pins 51 and the portions of the pins received in the bores 58 so as to damp vibration thereof hydraulically and thus reduce the noise incident to operation.

The openings 55 are of suflicient diameter to permit the maximum eccentricity of the rings relative to the barrel in either'direotion from the dead center position. a

By this arrangement standard drill stock rod may be used for the pins 51 and merely cut to length, ground at the ends and inserted. Thus the entire reactance assembly, including the dowel pins 51, is'held together by bolts 50. Correspondingly, the piston cross pins 42 are held in proper operating position thereby and rotation of the pistons about their own axes is prevented by the shoulders 42b. Due to the capillary cageless rollers 43, the frictional resistance to rotation of the pins about their own axes in-the bore of the crossheads is less than the rolling frictional resistance of the reduced end portions 42a in the operating. grooves 45 with the result that sliding of the end-portions 42a in the grooves is prevented. r

'By forming the reactance in this manner, both the stator and rotor can be made of forgings so as to provide both good race qualities and resistance to hydraulic load while at the same time reducingthe radial dimension of thestructure. The rings 45 are. also sturdy enough to offer substantially uniform resistance to elastic deforma- 'also foreign matter which comes in contact with the working parts is itself reduced and worn away instead of causing wear. or damage to the By forming the rotary reactance means in the manner provided, thedifferent problems of assembly and disassembly are eliminated; Obviously,all that is necessary to be done is to remove the end cover 2 of the housing, remove the control rods 52 and the entire operatingassembly can be removed from the housing. By.

removing the bolts 50 the reactance means can be separated and any part' that is worn may be replaced. Furthermore, both halves ofthe reactance means can be formed identically so that any .half will properly match and cooperate-with any other half. Again, in the caseiof any damage to any part of the reactance means or any roller or ball thereof it" is not necessa y. tQ replace the entire reactance but only the half that might be damaged. v

It is apparent from the foregoing; description that each part of the structure may readily be formedfrom readily available materials-by simple machining operations so that the resultant structure is both simple, durable, easily serviced andeconomical to manufacture, the number of working parts being reduced to a tor of the character described, comprising a pair of matched coaxial stator rings, each ring providing an outer bearing race, means detachably .connecting the rings rigidly together in said coaxial and end to'end relation, with their mutually adjacent faces abutting each other, a pair of matched reactance; rings correspondingly mounted one reactance ring'within and coaxial with each stator ring, each reactance ring providing an inner bearing race, sets of rolling bearing elements interposed one set between and indirect 'rollingengagement with each stator ring and associated reactance ring as races for rotatably supporting the associated reactance rings, said sets or bearings cooperating with the associated reactance rings to constrain the associated rings to fixed axial-and radial position with respect to the' stator rings, whereby each stator ring and associated reactance ring and elements provide a self-contained anti-friction bearing assembly,' said reactance rings having inner radial end; walls spaced apart axially when the stator rings are secured together, whereby portions of radial pistons to be cooperated with the rings may be [accommodated therebetween, and said spaced inner end: walls having aligned reactance grooves respectively therein opening toward the opposite one of said rings, whereby piston actuating pins of the said pistons to be associated therewith as the rings are drawn axially toward each other may be received axially in the grooves, said grooves being disposed closer to the axis of rotation of said stator rings and said reactance rings than said roller elements.

2. A rotary reactance unit 'for a pump or motor of the character described, comprising a pair of matched .coaxial stator rings, means for detachably connecting the rings rigidly together in end to end relatiorra pair of matched reactance rings" mounted one reactance 'ring'within and coaxial with each stator ring, radially aligned circumferential recesses in the inner circumferential surface of each stator ring and the outer circumferential surface of its associated reactance ring,- roller elements ,in the aligned recesses directly cooperating with the associated recesses to constrain eachstator ring and its associated reactance ring to 'flxed axial and radial position with respect to .each other and providing a self-contained anti-friction bearing assembly, said reactance rin'g's having inner radial end wallsspaced'apart axially when the stator rings are secured together, whereby portions of radial pistons to be'cooperated with the rings may be accommodated therebetween, and said spaced inner end" walls having aligned reactance groovesrespectively.therein and opening toward the opposite one of said rings, whereby piston actuating pins of the said pistons to be associated therewithas the rings are drawn axially toward each other may be received axially inthe grooves, the grooves being closer to the'common axis of said stator rings and said'reactance rings than said roller elements.

3. A rotary reactance unit for a pump or motor of the character described, comprising a pair of matched axially separable coaxial stator rings,

means for detachably connectingthe stator rings rigidly togetherin end to end abutting coaxial relation, 9. pair of matched reactance ringscorrespondingly mounted-one reactance ring .within and coaxial with each stator ring, sets of rolling elements interposed one set between each stator ring and associated reactance ring forrotatably supporting the associated reactance rings, said sets of bearings cooperating with the associated rings to constrain the associated rings to fixed axial and radial positionwith respect to each other, said reactance rings having inner radial end walls. spaced apart axially when the stator rings are connected together, whereby portions of radial pistons to be cooperated with the rings may be accommodated therebetween,

fand said spaced inner end walls having aligned reactance grooves therein extending parallel to the common iixis of'the rings and opening toward the opposite one of said rings, whereby actuating pins of the pistons to be associated therewith as the rings are drawn axially toward each other may be received in the grooves, each of said reactance rings having a plurality of bores extending parallel to their common axis and opening toward and aligned with the other, torque transmitting dowel pins received axially, one in each pair of said aligned bores and retained therein by the reactance rings, whereby the reactance unit may be readily assembled and disassembled axially.

4. In a rotary, radial piston pump or motor, a rotatable barrel having a plurality of radial cylinders, a radial flange on the barrel in the plane of the cylinders, and having radial guideways respective to the cylinders, valve means for the cylinders, pistons in the cylinders respectively and having heads operating in said guideways,

thrust pins carried by said heads and havingencl portions extending laterally therefrom at each face of the flange, and rotary reactance means eccentric to the barrel and cooperable with the thrust pins for actuating the pistons, said reactance means comprising a pair of coaxial stator rings detachably secured together in end to end abutting relation at the plane of the pistons and axially separable from each other, means for detachably connecting said rings to each other, reactance rings anti-frictionally' mounted one in each stator ring and spaced axially from each other and accommodating the barrel flange and piston heads therebetween, reactance grooves in said reactance rings opening toward the barrel flange and receiving the laterally extending end portions of the pins for cooperation therewith to I actuate the pistons, holes in said barrel flange positioned radially of the flange in alignment with the grooves, bores in each reactance ring in the groove thereof and opening toward the opposite .reactance ring and extending parallel to the axis of rotation, each bore being-aligned with a bore of the opposite reactance ring, and cylindrical dowel pins extending through the barrel flange holes and received at their ends, one. in each position by pair of aligned bores, and heldJn the reactancerings. r

5. In a rotary, radial piston pumpor motor, a rotatablebarrel having a plurality of radial cylinder s, a radial flange on the barrel in the plane of the cylinders, and having radial guideways respective to the cylinders, valve means for the cylinders, pistons in the cylinders respectively and having heads operating in saidguid'eways,

thrust pins carried by saidvheads and having end I portions extending laterally therefrom at each face of the flange, and rotary reactance means eccentric to the barrel and cooperable with the thrust pins for actuating the pistons, said r actance means comprising a pair of coaxial stator rings detachably secured together in end to end abutting relation .at the plane of the pistons and axially each cross pin comprising a large diameter cenpositioned radially oi the flange in alignment with the grooves, bores in each reactance ring in the groove thereof opening toward the opposite reactance ring and extending parallel to the axis of rotation; each bore being aligned with a bore of the opposite reactance ring, cylindrical dowel pins extending through the barrel flange holes and received at their ends, one in each pair of aligned bores, and held inposition by the reactance rings, each of said dowel pins being accommodated in said bores with slight radial clearance.

6. In a rotary, radial piston pump'or motor, a

rotatable barrel having a plurality of radial cylinders, a' radial flange on the barrel in the plane of the cylinders, and having radial guideways respective to the cylinders, valve means for the cylinders, pistons in the cylinders respectively and having heads operating in said guideways,

thrust pins carried by said heads and having and portions extending laterally therefrom at each face of the flange, and rotary reactance means eccentricto the barrel and cooperable with the thrust pins, for actuating the pistons, said reactance means comprising a pair of coaxial stator rings detachably secured together in end to end abutting relation at the. plane of' the pistons and axially separable from each other, means for detachably' connecting said rings to each other, reactance rings anti-frictionally mounted one in each stator ring and spaced axially from each other and accommodating the barrel flange and piston heads therebetween, reactance grooves in said reactance rings opening toward the barrel flange and receiving the laterally extending end portions of the pins for cooperation therewith to actuate the pistons, bores in said barrel flange positioned radially of the flange in alignment with the grooves, holes in each reactance ring in the groove-thereof and opening toward the opposite reactance ring and extending parallel to the axis of rotation, each hole being aligned with a hole of the opposite reactance ring. cylindrical dowel pins extending through the barrel flange bores and received attheir ends, one in each pair I of aligned holes, and held in position by the reactance rings, and said dowel pins engaging the end walls, of the associated bores for holding said reactance rings apart.

'7. In a rotary radial piston pump or motor, a rotatable barrel having a plurality of radial cylinders, pistons in the cylinders respectively, valve means for the cylinders, each piston having a crosshead with a transverse bore therethrough parallel to the'barrel axis, a flange on the barrel having radial ways respective to the crossheads, a rotary'reactance means surrounding the barrel and mounted for adjustment to diilerent positions of eccentricity relative thereto and including a pair of actuating rings spaced, apart axially from each other for accommodating the piston crossheads therebetween with operative clearance, reactance grooves in the rings opening toward the pistons and aligned with each other, cross'pins carried by the pistons respectively,

barrel, whereby radial shoulders are formed on 40 each cross pin at the junctureot. said-large and tral portion substantially coextensive with the crosshead bore and anti-'frictionally supported therein substantially continuously along its length, and end portions of less diameter extend- 5 ing axially of the pin from the large diameter portion beyond the radial limits of the respective piston heads and flange, whereby radial-shoulders are formed on the cross pin at the juncture of said large and small diameter portions; said 19 extending end rtions being received in said grooves respect vely, and said rings having radial faces alongside the pistons in relatively rolling engagement with said shoulders and constraining the pins from skewing about the axes ofthe associated pistons, respectively.

. 8. Ina rotary radial piston pump or motor, a rotatable barrel having a plurality of radial cylinders, pistons in the cylinders respectively, valve means for the cylinders, each piston having a crosshead with a transverse bore therethrough parallel to the barrel axis, radial guide means on the barrel respective to the crossheads, a rotary reactance means surrounding the barrel and mounted for adjustment to different positions 01' grooves in the walls opening toward the pistons and aligned with each other; cross pins carried by the pistons respectively, each crosspin comprising a large diameter central portion antifrictionally mounted in and substantially coextensive-with the crosshead bore of the associated piston, and having end portions of less diameter extending axially oi the pin from the large diameter portion beyond the limits of the associated piston head, and the said guide means on the small diameter portions oreach pin, said extending end portions being received in said grooves respectively, said walls having radial ,face portions alongside the pistons in relatively 5 rolling engagement with said shoulders and con.-

straining the pins respectively from rotation about the axes of their associated pistons respectively, the'said shoulders and reduced end portions being joined by a short radius curved surface, and the edges at the juncture of the grooves and said radial face portions being joined by a short radius curved surface diilerent from first mentioned curved surface.

9. In a radial piston rotary'reactance or motor including a casing, a rotor, piston and cylinder assemblies carried thereby, valve meansfor the assemblies, laterally extending thrust means carried by the assemblies, a reactance rotor operatively engaging the thrust means for operating the assemblies, said reactance rotor comprising a pair of complete self contained anti-friction. bearing assemblies positioned at opposite sides of the plane or the piston and cylinder assemblies, each be eluding an outer race, an friction elements carried thereby between said races, means independent or said casing rigidly connecting the outer races of said bearing assemblies together, said outer races being directly v 10. In a rotary radial piston pump or motor,

g assembly in.- er race and anti- Sil . means on said members a casing; a rotary reactance sub-assembly disposed within the casing and comprising a pair of self-contained anti-friction bearing assemblies, each bearing assembly comprising a stationary race member, a relatively rotatable onepiece race member coaxial therewith, and antifriction elements between the race member-sand in direct rolling cooperation therewith, react'ance grooves formed directly in the relatively rotating race members and positioned inwardly towardary race members, relatively rotating racemem bers. anti-friction bearing elements in direct rolling engagement with the associated station ary and relativelyrotating race members and supporting eachrotating member within an. associated stationary member, said relatively rotating members having axially spaced radial faces and normally aligned grooves in said faces, cooperating with the associated bearing elements for constraining each stationary race member and its associated relatively rotatable race member 'i'rom relative axial separation, said-stationarymembers and. associated rotating members with the associated bearing elements providing a pair oi. axially sepin the casing.

bers being spaced arable self-contained anti-friction hearing assemblies, means independent of said casing rigidly connecting said stationary race members together, and means mounting the subassembly 1 2. In a reactance assembly for a radial piston pump or motor, a casing, a pair of stationary members, means independent of the casing rigidly connecting said stationary members to-' gether, rigid relatively rotating members carried 1 one by each stationary .member; sets of radial anti-friction bearing elements disposed between associated stationary and relative rotating members and in direct rolling engagement with adjacent surfaces of the members for supporting one 15 within the other, said relatively rotating memaxially from each other toprovide an axial clearance space between adjacent faces of the relative rotating members, normally aligned grooves directly in saidrelatively rotating members and opening through said ad'- jacent faces and arranged radiallywith respect to the axis of said members close to the path of v I the bearing elements, said stationary and relatively rotating membershaving bearing grooves 25 receiving said anti-friction elements whereby said elements serve to maintain each stationary member and its associated'relatively rotating member against axial separationand forming with the associated sets of radial antifriction 3 bearing elements a plurality of axially spaced? and coaxially disposed separable salt-contained complete anti-friction bearing, sub-assemblies, and means mounting said pair or stationary members in the casing.

ELEK K. BENEDEK. 

